In the context of subjective eye tests, a visual compensation device is generally used to allow observation along an optical axis of observation with an optical correction of variable power.
For example, such a device is for example known from document US 2004/032 568; this device comprises a lens having, along the optical axis, a variable spherical power that depends on a first setting, and an optical assembly generating, along the optical axis, a variable cylindrical correction that depends on at least one second setting applied to said optical assembly.
In such a system it is for example proposed to display on a screen the optical correction values obtained by applying current settings, thereby allowing the practitioner to modify the settings to obtain other optical correction values.
This solution is however impractical since it obliges the practitioner to find by trial and error the visual correction values that he desires to test during the subjective eye test.